Routers route packets across the Internet using a routing table. A routing table (or routing information base (RIB)) can include optimal paths toward individual routing prefixes. A router can insert a route into the RIB whenever the router learns of the new route. But, routers do not use the RIB to forward packets; rather, a forwarding information base (FIB) is used to forward packets.
A FIB can be a database that includes forwarding entries representing an outgoing interface and next hop information for each reachable destination routing prefix. If not all the forwarding entries can be stored in the FIB, then the router may drop traffic to destinations not programmed in the FIB.
In the drawings, like reference numbers generally indicate identical or similar elements. Additionally, generally, the left-most digit(s) of a reference number identifies the drawing in which the reference number first appears.